Parth
e7d75c3b05
* Rewrite comments in Google developer documentation style Rewrite the comments and docstrings across the backend core modules so they read plainly. The previous prose was accurate but dense and figurative, which made it slow to skim. Applies the Google developer documentation style guide: short sentences, active voice, present tense, American spelling, and no metaphors, idioms, or rhetorical asides. Replaces em-dash chains with separate sentences.
48 lines
2.2 KiB
Python
48 lines
2.2 KiB
Python
"""Make a database look like an older schema version, so a migration can run.
|
|
|
|
`create_all` always builds the current schema. A test that wants to watch a
|
|
migration run must remove the newer columns first and then stamp an older
|
|
version. Otherwise the migration finds a column that already exists and
|
|
fails on a duplicate.
|
|
|
|
Rewinding the stamp alone worked for a while, so two test files did exactly
|
|
that. It stopped working when another `ADD COLUMN` migration landed. Without
|
|
this rewind, the replay runs migrations the tests never intended to
|
|
exercise, against columns `create_all` already added. This module rewinds
|
|
properly in one place. Adding a migration now means adding its inverse here,
|
|
instead of tracking down failures in three unrelated test files.
|
|
|
|
This module supports SQLite only. Every test that replays migrations runs on
|
|
a temp file, and SQLite stores the stamp in `PRAGMA user_version`.
|
|
Migrations that change a column's type (43-45, JSON to compressed bytes)
|
|
have no clean inverse, so this list omits them. Those migrations replay
|
|
as-is, which is what the tests using them already expect.
|
|
"""
|
|
|
|
from sqlalchemy import text
|
|
from sqlalchemy.engine import Engine
|
|
|
|
# Each entry is (version that added the column, statements that remove it).
|
|
# The list is ordered newest first.
|
|
#
|
|
# Phase 14's `branch_id` columns are missing on purpose. SQLite refuses to
|
|
# drop a column that a foreign key references, so a current-schema database
|
|
# cannot be rewound past them. `migrations._column_already_there` handles
|
|
# this case. It skips DDL that already ran, so the tree migrations run their
|
|
# backfill against a schema that already has the columns.
|
|
_UNDO: list[tuple[int, tuple[str, ...]]] = [
|
|
# Packed float32 vectors and the flag beside them.
|
|
(39, ("ALTER TABLE memories DROP COLUMN embedded",)),
|
|
(38, ("ALTER TABLE memories DROP COLUMN embedding_blob",)),
|
|
]
|
|
|
|
|
|
def rewind_to(engine: Engine, version: int) -> None:
|
|
"""Drop everything added after `version`, then stamp the database at it."""
|
|
with engine.begin() as conn:
|
|
for added_at, statements in _UNDO:
|
|
if added_at > version:
|
|
for sql in statements:
|
|
conn.execute(text(sql))
|
|
conn.execute(text(f"PRAGMA user_version = {version}"))
|